# Pre-Aggregations

The Pre-Aggregations page in Cube Cloud allows you to inspect all
[pre-aggregations][ref-caching-gs-preaggs] in your deployment at a glance. You
can see which pre-aggregations are accelerating queries, if they are [being
refreshed][ref-caching-using-preaggs-refresh], along with the last 24 hours of
build history.

<SuccessBox>

The Pre-aggregations page is available in Cube Cloud on
[all product tiers](https://cube.dev/pricing).

</SuccessBox>

<Screenshot src="https://ucarecdn.com/eb10de99-4ff6-4a9f-abd5-736971497583/" />

## Exploring pre-aggregations

You can switch between [pre-aggregations](#pre-aggregations) and
[build history](#build-history) by switching between the 
​<Btn>Pre-Aggregations</Btn> and <Btn>Build History</Btn> tabs.

## Pre-aggregations

The <Btn>Pre-Aggregations</Btn> tab shows a list of all configured
[pre-aggregations][ref-caching-gs-preaggs] for the deployment, and is useful for
quickly checking details such as when the last build occurred, how long the
build took to complete, the total size of the pre-aggregated data, and how many
partitions the data is split across. To see more information about a specific
pre-aggregation, click on it.

### Partitions

The <Btn>Partitions</Btn> tab shows all partitions (as specified by
[`partitionGranularity`][ref-model-ref-preaggs-partition-granularity]) of the
pre-aggregation. In the example below, the pre-aggregation has a single
partition:

<Screenshot src="https://ucarecdn.com/d65d5910-3561-4101-9317-2c9f8366694e/" />

Pre-aggregations with multiple partitions show a list of all partitions, which
is helpful for checking pre-aggregation partition build times and sizes:

<Screenshot src="https://ucarecdn.com/84c2989b-cbd1-469c-aca6-127fc97f074b/" />

Ideally partitions should be of a similar size and build time. If a partition is
taking significantly longer to build than others, it may be worth investigating
why.

If the pre-aggregation requires rebuilding (usually due to the underlying data
changing in a significant way), clicking <Btn>Build All</Btn> rebuilds **all**
partitions of the pre-aggregation:

<Screenshot
  highlight="inset(41% 1% 54% 91% round 10px)"
  src="https://ucarecdn.com/d65d5910-3561-4101-9317-2c9f8366694e/"
/>

You can also choose to rebuild **specific** partitions by selecting them and
then clicking the <Btn>Build Selected</Btn> button:

<Screenshot
  highlight="inset(52% 88% 0% 7% round 10px)"
  src="https://ucarecdn.com/99c72537-51d4-44ce-8df1-ea1a9cc3feaf/"
/>

### Definition

The <Btn>Definition</Btn> tab shows how the [pre-aggregation is defined in the
data model][ref-model-ref-preaggs] without having to switch to the <Btn>Data
Model</Btn> page:

<Screenshot src="https://ucarecdn.com/4e8f203a-bd6b-4316-86ff-b742ccbc78a4/" />

### Preview

To see a sample of the data contained in the pre-aggregation, click the 
​<Btn>Preview</Btn> tab:

<Screenshot src="https://ucarecdn.com/7f5059bb-3bc9-492e-9c69-3b614f3feca5/" />

This can be used to verify that the data within the pre-aggregation is being
built correctly.

### Used By

The <Btn>Used By</Btn> tab shows recent queries that used this pre-aggregation
for acceleration:

<Screenshot src="https://ucarecdn.com/1dcef348-af33-434a-9ef7-7a4c5f30c26c/" />

This is especially useful for checking that the pre-aggregation is being used as
expected by queries sent to the deployment.

### Indexes

[Indexes][ref-model-ref-preaggs-index] significantly improve the performance of
configured pre-aggregations. The <Btn>Indexes</Btn> tab displays any configured
indexes for this pre-aggregation:

<Screenshot src="https://ucarecdn.com/f7e306e2-4245-46b4-8785-3e7fc1be518e/" />

## Build History

The <Btn>Build History</Btn> tab shows the last 24 hours of build history for
all pre-aggregations in the deployment. From here, you can see if a
pre-aggregation build succeeded (or failed), how the build was triggered, when
the build started, and how long it took to complete.

<Screenshot src="https://ucarecdn.com/9a9f88fb-9977-4aed-a0a8-52494d1d8e6b/" />

To see more information about a specific build, click on it:

<Screenshot src="https://ucarecdn.com/2f2d4366-35a6-42be-aac6-f554d824f8d3/" />

[ref-caching-gs-preaggs]: /product/caching/getting-started-pre-aggregations
[ref-caching-using-preaggs-refresh]:
  /product/caching/using-pre-aggregations#refresh-strategy
[ref-model-ref-preaggs]: /product/data-modeling/reference/pre-aggregations
[ref-model-ref-preaggs-index]:
  /product/data-modeling/reference/pre-aggregations#indexes
[ref-model-ref-preaggs-partition-granularity]:
  /product/data-modeling/reference/pre-aggregations#partition_granularity
